During the thirteenth year of support, Program-project 08682 investigators studied mechanisms of cardiovascular regulation with specific emphases from ten different points of view, including central, spinal and peripheral nervous control, biochemical and metabolic regulation, endotoxin and hemorrhagic shock, cardiopulmonary integration and control, mechanics of blood vessel function, the microcirculation, renal circulation and hypertension, catacholamine metabolism, and hibernation. These ongoing experimental thrusts will be augmented during the fourteenth year by additional probes into the biochemical aspects of lung metabolism, the dynamics of pulmonary circulation, and the metabolic bases for arousal in the hibernating animal. Emanating from the research are descriptions of animal models of cardiac dysrhythmia based upon surgically imbalanced autonomic innervation of the heart, the function of subsidiary atrial pacemakers in the absence of the SA node, and structure-functional descriptions of spinal pathways mediating cardiovascular reflexes. Papers describing the role of angiotensin II in renal hypertension, development of longitudinal retraction of cartotid arteries in neonatal dogs, and overdrive suppression of atrial and junctional pacemakers during sympathetic activation further illustrate the output of the Program. In addition, alterations in glucose utilization during endotoxemia, influences of coronary occlusion on pulmonary vascular resistance, intracellular potential recordings from phrenic motoneurons during spontaneous orthodromic activation and coding patterns of lingual thermoreceptors of the cat were described. Fluorescense histochemistry techniques have revealed important alterations in sympathetic innervation of the heart during hibernation and the implications of this system to arousal are being pursued. Chemical identification of the "trigger" substance, functional in the induction of hibernation, as an important ongoing research emphasis.